1. Field of the Invention
This invention relates generally to electrical switching apparatus, and in particular to an improved structure for the stationary contacts of such apparatus.
2. Description of the Prior Art
German Pat. No. 623,700 discloses a switching apparatus including electrical contacts constructed of non-magnetic material and arc conducting members constructed of ferromagnetic material. In that apparatus, a pin shaped switch contact, which is constructed of copper, bronze or brass, is provided with a recess at an end face thereof not suited for the formation of a permanent contact. A ferromagnetic member, constructed, for example, of iron, is disposed in this recess in order to cause the bases of electrical arcs generated during opening of the switching apparatus to move away from the switch contacts by means of electromagnetic force. Such a structural arrangement, i.e., one including a ferromagnetic member, is costly and can be utilized only in conjunction with heavy switching contacts.
German Pat. No. 317,407 discloses an electrical switching apparatus in which a contact carrier member is constructed of less electrically conductive material than the contacts and which includes an electrically conductive plating of copper or brass disposed in the regions thereof which affect current transfer and interruption. The plating is applied in a thickness which is sufficient to render the electrical resistance thereof low and the durability thereof high with respect to damage caused by arcing. Thus, the contact carrier of this apparatus does not serve as an arc conducting bar.